How do i make a TextBox only accept numbers?

Hello, i dont have a code, but how do i make the textbox only accept numbers? Like, when you type in a letter, the letter doesnt appear in the text box, but when you type in a number, the number appears in the textbox. I already searched the wiki, but theres nothing. Help?

IM NOT SURE IF THIS WILL HELP TOO MUCH If you can't make the GUI to only accept numbers in the script. Then try making a easier script like a little code paddy. So when you click the numbers on the bricks or the GUI in a certain order after you press enter it checks it and then if its right then it does what ever, else it goes back to the beggining

I guess what you can do is make buttons for each number and put individual text labels and everytime you click a number it'll change one of the labels.